Spanning 14 movements and well over two hours long, it's a big-canvas piece, a sprawling orchestra and percussion ensemble work inspired by the storied, centuries-old New Orleans marketplace where, on Sundays, African slaves were once allowed to play music, sing and dance. When you consider how such a meager liberty could produce such profound cultural reverberations -- in effect, laying the groundwork for myriad forms of artistic expression -- it's tempting to view "Congo Square" as a joyous celebration of unintended consequences. Of course, it's also a favorite son's homage to the Crescent City.

When "Congo Square" was presented by the Washington Performing Arts Society at the Kennedy Center Concert Hall on Tuesday night, Marsalis never picked up his trumpet. Instead, he served as conductor, choirmaster, referee and witness, standing between the Lincoln Center Jazz Orchestra and Addy's remarkable percussion and voice ensemble, Odadaa!.

Marsalis briefly chanted -- early on, he bemoaned FEMA's sorry response to Hurricane Katrina -- and strutted in place whenever the sharply syncopated grooves moved him. But he spent most of the concert firing off cues to the ensembles, which were often pitted against each other in vibrantly colorful fashion. Any fears that Odadaa! would be relegated to a supporting role quickly vanished, as one powerfully rhythmic surge followed another.

There's nothing linear about "Congo Square." Many of the movements could have been shuffled without losing the overall effect. (A little trimming here and there wouldn't hurt, either.) Instead of tracing the marketplace's evolution and influence, Marsalis and Addy have created a bustling collage, riddled with dramatic contrasts that juxtapose complex African rhythms with early jazz polyphony, Ellingtonian vignettes, heartsick balladry, clave-accented grooves, second-line parade beats and sanctified blues. There was no shortage of appealing melodies -- sunny, soulful and whimsical by turns -- or delightful showcases for Odadaa! and numerous members of the LCJO, including drummer Ali Jackson, pianist Dan Nimmer and reedman Victor Goines.

Marsalis plans to record "Congo Square" soon, but of all his extended works, this one seems most likely to become a summer festival season favorite. Indeed, in many ways, it's a festival unto itself.